Microsurgical procedures frequently require precision cutting and/or removing of various body tissues. For example, certain ophthalmic surgical procedures require cutting and removing portions of the vitreous humor, a transparent jelly-like material that fills the posterior segment of the eye. The vitreous humor, or vitreous, is composed of numerous microscopic fibrils that are often attached to the retina. Therefore, cutting and removing the vitreous must be done with great care to avoid traction on the retina, the separation of the retina from the choroid, a retinal tear, or, in the worst case, cutting and removal of the retina itself. The cutting and removal of membranes may be particularly difficult in some delicate operations, such as mobile tissue management (e.g., cutting and removal of vitreous near a detached portion of the retina or a retinal tear) and vitreous base dissection.
Handheld surgical instruments, such as microsurgical forceps or scissors, may be used to cut and/or remove various body tissues. Generally, handheld instruments on the market are manually actuated. That is, the hand or fingers of a user, such as a surgeon or other medical professional, are pressed with force against a mechanism in the instrument handle to actuate the instrument tip.
During actuation, it is essential that the instrument tip remains stable near the target anatomy within the eye. Manual actuation is not ideal for surgeons because they can feel the friction and/or hysteresis of the actuation mechanism in their hands or fingers. Additionally, stick-slip effects or unintended, spontaneous movement of the instrument tip can occur. As a result, to achieve stable tip positioning, the surgeon must carefully coordinate actuation and positioning of the tip by filtering out the friction, hysteresis, and/or stick-slip effects, and by minimizing movement of the surgical device. Requiring that one or more fingers be pressed with force to actuate the instrument tip also has a negative influence on the precision of the surgical tasks, such as grasping or peeling of anatomy.
A pneumatic system is an alternative to the manually-actuated systems described above. In a pneumatic system, actuation of the instrument tip can be achieved, for example, via depression of a foot pedal. While this type of system solves some of the challenges above by removing actuating motion from the surgeon's hands, it still requires a level of coordination between hand and foot.